This application is based on and claims priority to Japanese Patent Application No. 2002-016296, filed on Jan. 25, 2002, the entire contents of which is hereby expressly incorporated by reference herein.
1. Field of the Invention
The present invention generally relates to a vertically extendable arrangement for a marine propulsion device, and more particularly relates to an improved arrangement for a marine propulsion device in which a driveshaft of the propulsion device is vertically extendable so as to be capable of being used in multiple housings of differing lengths.
2. Description of Related Art
Marine propulsion device such as, for example, outboard motors incorporate an engine as a prime mover to power a marine propelling unit. The propelling unit typically is a propeller and is submerged when an associated watercraft rests on a body of water. The engine typically is placed atop the outboard motor. A drive train and a transmission couple the engine with the propelling device. Typically, the engine has a crankshaft that extends generally vertically. The drive train includes a driveshaft below the engine. The driveshaft also extends generally vertically and is connected to the crankshaft to transfer the power of the engine to a propulsion shaft, which also forms a portion of the drive train. The transmission selectively couples the propulsion shaft with the driveshaft.
Typically, the driveshaft for the outboard motors extends within a housing unit. The driveshaft and the housing unit normally have a specific length. The associated watercraft, however, can have various sizes. Thus, the driveshaft and the housing unit can be shorter than a height of the associated watercraft. If the driveshaft and the housing unit are shorter than the height of the watercraft, the propelling unit tends to be placed higher than a desired position on the watercraft. Accordingly, in some applications, both the driveshaft and the housing unit need to be lengthened such that the propelling unit is disposed at a suitable position relative to the watercraft hull.
In order to elongate the length of the driveshaft, for example, the driveshaft can be divided into upper and lower sections and two types of upper section, i.e., regular size and longer size upper sections, can be prepared. Either the regular size or longer size upper section is selected in accordance with the height of the associated watercraft. A housing extension member also is prepared to elongate the housing unit to accommodate the longer size upper section when selected.
FIG. 1 illustrates an exemplary construction defined within a housing unit 20. The housing unit 20 comprises a driveshaft housing 22 and a lower unit 24. A driveshaft 26 is divided into an upper section 28 and a lower section 30. As noted above, two types of the upper section 28 can be provided. In the illustrated arrangement, the upper section 28 has a regular size. No extension housing thus is applied in this arrangement. The upper and lower sections 28, 30 can be coupled with each other through a spline connection. That is, a bottom end of the upper section 28 and a top end of the lower section 30 define key ways. A tubular coupling member 34 also defines key ways on an inner surface thereof. The key ways of the coupling member 34 engage the key ways of the upper and lower sections 28, 30 to complete the spline connection.
Generally, the key ways need to be long enough to ensure a necessary strength of the connection. The driveshaft, however, is journaled by a bearing assembly in the housing unit. Also, the drive shaft drives an auxiliary device such as, for example, a water pump. Thus, it often is difficult to design the coupling member with sufficient length without interfering with auxiliary devices and bearing assemblies.
A need therefore exists for a vertically extendable arrangement for a marine propulsion device that can ensure the strength of the connection between sections of a driveshaft.
An aspect of the present invention involves a marine propulsion device comprising at least first and second housings and first and second shafts. At least a portion of the first shaft extends through the first housing and at least a portion of the second shaft extends through the second housing. The first shaft drives the second shaft, and one of the shafts drives a rotatable member. The first and second shafts are coupled together by a tubular coupling member. The first shaft includes a plurality of external splines that are disposed at least near one of its ends and the second shaft also including plurality of external splines that are disposed at least near one of its ends. The tubular coupling member defines a plurality of internal splines. The splines of the coupling member engage the splines of the first and second shafts to couple together the first and second shafts. The coupling member is also disposed between the rotatable member and whichever one of the first and second shafts drives the rotatable member.
Another aspect of the present invention involves a marine propulsion device comprising at least first and second housings. The second housing is disposed below the first housing. At least a portion of a first extends generally vertically through the first housing. The first shaft drives a second shaft. At least of portion of the second shaft extends generally vertically through the second housing. Either the first or second shaft defining a recess. The second or first shaft that does not define the recess defines a tip portion that is inserted into the recess. The recess defines a first plurality of key ways on an inner surface thereof and the tip portion defines a second plurality of key ways on an outer surface thereof. The respective first and second key ways are engaged with one another to couple together the first and second shafts.
In accordance with an additional aspect of the invention, a marine propulsion device is provided that comprises a prime mover having an output shaft, which extends generally vertically, and first, second and third housings. The second housing is disposed below the first housing, and the third housing is disposed below the second housing. A first shaft is driven by the output shaft. At least a portion of the first shaft extends generally vertically within the first housing, and the first shaft drives a second shaft. At least a portion of the second shaft extends generally vertically through the first, second and third housings. The output shaft and the first shaft are coupled together by a first spline coupling, and the first and second shafts are coupled together by a second spline coupling.
In accordance with an additional aspect of the present invention, a marine propulsion device comprises at least first and second housings. The second housing is disposed below the first housing. A first shaft is provided. At least a portion of the first shaft extends generally vertically through the first housing. A second shaft is driven by the first shaft. At least a portion of the second shaft extends generally vertically through the second housing. A pump unit is driven by either the first or second shaft. The pump unit comprises a pump housing surrounding the first or second shaft. The first and second shafts are coupled with each other within the pump housing.
In accordance with another aspect of the present invention, a marine propulsion device comprises at least first and second housings. The second housing is disposed below the first housing. A first shaft is provided and at least a portion of the first shaft extends generally vertically through the first housing. A second shaft is driven by the first shaft. At least a portion of the second shaft extends generally vertically through the second housing. A coupling member joins the first and second shafts together, and a bearing unit journals the coupling member within one of the housings.